1. Field of The Invention
This invention relates to the art of fiber-reinforced slag gypsum cement and more particularly, to a method for fabricating fiber-reinforced slag gypsum cement-based, lightweight set articles or products which are useful as outside and inside wall materials of buildings and which have good water resistance, durability and fire resistance.
2. Description of The Prior Art
Hitherto known lightweight building materials have included gypsum building materials, typical of which are gypsum boards utilizing setting of hemihydrate gypsum and anhydrous gypsum. Gypsum/slag and gypsum/slag/cement composite building materials have now been put on the market. Moreover, there have been proposed quick-setting cement compositions composed of Portland cement, alumina cement, gypsum and lime. Recently the composition has been used to make woody cement sheets or plates. Besides, there are known autoclaved lightweight building materials, typical of which is ALC (autoclaved lightweight concrete).
Conventional gypsum building materials make use of setting and hardening characteristics of hemihydrate gypsum, with an attendant advantage that they can be shaped or molded and processed within a short time. However, since the gypsum building material is mainly composed of gypsum, there arises the problem that the water resistance is poor. To improve the water resistance, gypsum/slag or gypsum/slag/cement composite building materials are now commercially sold. However, in order that these composite building materials are molded and processed within a short time, a substantial amount of hemihydrate gypsum has to be employed, leaving the problem of the water resistance. On the contrary, when the amount of hemihydrate gypsum is reduced, the molding and processing within a short time is not possible although the problem of the water resistance can be solved.
The use of quick-hardening cement compositions composed of Portland cement, alumina cement, gypsum and lime enables one to mass-produce within a short time building materials with a great degree of freedom with respect to the shape and the thickness. However, the building material produced from the above four ingredients is disadvantageous in that when the amounts of the four ingredients are varied only slightly, the dimensional stability will become poor or the long-term durability will be degraded. For the continuous mass production of conventional cement building materials, a sheet making process is used or curing in an autoclave is necessary. In the former process, it will be difficult to produce building materials whose thickness exceeds 20 mm. In the latter case, there are involved problems that site processability or workability such as cutting, nailing and the like is not good with a vast cost for the equipment.
We proposed in Japanese Patent Application No. 1-139647 a method for fabricating a novel fiber-reinforced slag gypsum cement-based lightweight set product. However, it was found as a result of further studies that the building material set forth in the above application was not satisfactory with respect to the dimensional stability in outdoor exposure and coarse bubbles (with a diameter of not smaller than 1 mm) involved during kneading and molding of slurries.